This invention relates to a load moving machine, such as a hydraulic excavator, in which a front attachment having a plurality of linkage elements is driven for moving a load, and more particularly it is concerned with a load weight indicating system for such load moving machine.
A load moving machine, such as a hydraulic excavator, provided with a front attachment having a plurality of linkage elements often performs the operation of moving a load from one position to another. This operation will be described by taking a hydraulic excavator as a typical example of such load moving machine.
Assume that a hydraulic excavator performs the operation of digging the earth to make a hole and loading a dump truck with sand removed from the earth. The operator of the excavator would suitably drive a boom, a shovel and a bucket of the hydraulic excavator to place in the bucket the sand removed from the earth and move an upper swing in swinging movement to transport the bucket to the dump truck standing by, to load the dump truck with the sand.
When this type of operation is performed, it has hitherto been usual practice to rely on measurements made by the operator with his eye to determine the weight of the load. Meanwhile, a dump truck has a rated loading capacity, and it has usually been the case that, when the weight of the load is merely measured with the eye of the operator, the load of the truck is greater or smaller than the loading capacity. Thus, when a load of sand placed on a dump truck actually exceeded or did not reach the rated loading capacity, problems would arise. If the load exceeded the loading capacity, trouble might occur in the dump truck and the dump truck might be involved in accident, thereby reducing its service life. Conversely, if the load were below the loading capacity, operation efficiency would drop.
In another type of operation of moving a heavy load by a hydraulic excavator, the hydraulic excavator has been used for feeding a large amount of limestone into a reaction furnace of a chemical plant. In this case, the weight of the limestone necessary for causing a reaction to take place is predetermined, so that it has been usual practice to measure the weight of the limestone before dumping same into the furnace by means of the dump truck. This is time-consuming and labor-wasting.